After moving to the University of Kentucky, that is for the latter three years of this Grant period, I will continue with my studies of the interactions between circulating granulocytes, plasma complement and the vascular endothelium. Based on our studies of the leukopenia which occurs during hemodialysis and nylon fiber leukapheresis, we concluded that intravascular complement activation results in peripheral granulocytopenia, and pulmonary leukostasis. The fragment responsible is C5a(desarg), which causes reversible aggregation of circulating granulocytes and pulmonary embolization of the aggregates so formed. The aggregated granulocytes, produce lung dysfunction in vivo and damage endothelial monolayers in vitro, primarily by releasing toxic oxygen species (superoxide, hydrogen peroxide, singlet oxygen). My plan as stated in my original proposal remains essentially unaltered by my move; it is to explore many of the ramifications of this newly-described mechanism of tissue injury. At the cellular level in vitro, I plan to further define the mechanisms whereby C5a(desarg) (and other chemotactic stimuli) augments adhesiveness and causes granulocytes aggregation, and the ways in which embolized aggregates disrupt endothelial integrity. I hope to define the clinical relevance of C5a-mediated granulocytes sequestration as a mechanism for otherwise-unexplained granulocytopenia in patients with auto-immune disease and for the organ damage associated with disseminated intravascular complement activation in patients with shock (due to sepsis, burns, trauma, endotoxinemia) or during graft-versus-host reactions (following bone marrow transplantation). I have already begun to develop granulocyte aggregometry as an objective bio-assay for C5a(desarg) by incorporating a digital integrator into the assay system, and I plan to continue to develop this now quantitative method to detect circulating levels of C5a(desarg) in patients with disseminated intravascular complement activation. Although there will be an inevitable lag of 1-2 months due to the moving process, my newly refurbished laboratory at the University of Kentucky and the other facilities available to me will more than adequately replace my present laboratory, and I have taken particular care to recruit three very qualified new collaborators to replace those with whom I have worked in Minneapolis.